BRD4 and acute myeloid leukemia: Also, to rule out the possibility that BRD4 isoform switching was a consequence (rather than the cause) of myeloid differentiation, we treated THP-1 cells with two drugs known to drive AML differentiation MI-50319 and cytarabine (Ara-C)18, and observed no effect on BRD4 isoform ratio; whilst we also failed to see an effect upon iBET-151 treatment (Supplementary Fig. 9n).